Explanation: The Mongols ruled Russia as if it were a protection racket, exacting tribute from the Russian principalities but leaving direct administration to the princes themselves. This matches (B). Eliminate (A) because the Russian Mongols eventually converted to Islam. Eliminate (C) because the Russians chafed under Mongol rule and revolted themselves. Finally, eliminate (D) because the Mongols stimulated Chinese production and economic activity as much as possible for their own taxation purposes.